It fills the depression points present within a DEM so that
the drainage directions are defined in each point.
<br>
<br>
<h3>Inputs</h3>
<ul>      
<li>the file containing the elevations</li>
</ul>
<br>
<br>
<h3>Output</h3>
<ul>      
<li>the file containing the corrected elevations</li> 
</ul>
<br>
<br>
<h3>Notes</h3>
The flooding algorithm (pitfiller) fills all pits present in the DEM.
Obviously these could be real and not a product of gridding the landscape.
In this case we should find a representation of the drainage
directions considering also the possible lakes and ponds, which is not
yet implemented.
